1. Field of the Invention
The invention relates to a non-contact power receiving/transmitting device and a manufacturing method therefor and, more particularly, to a non-contact power receiving/transmitting device of which the resonance frequency is adjustable by a resonance method and a manufacturing method therefor.
2. Description of the Related Art
In recent years, as an environmentally friendly vehicle, a vehicle that is equipped with an electrical storage device (for example, a secondary battery, a capacitor, or the like) and that is propelled by driving force generated from electric power stored in the electrical storage device becomes a focus of attention. Such a vehicle, for example, includes an electric vehicle, a hybrid vehicle, a fuel cell electric vehicle, and the like.
There is known a hybrid vehicle that is able to charge an in-vehicle electrical storage device from a power supply outside the vehicle as in the case of an electric vehicle. For example, there is known a so-called plug-in hybrid vehicle that is able to charge an electrical storage device using a power supply of an ordinary household in such a manner that a power supply wall outlet installed in a house is connected to a charging inlet provided for a vehicle via a charging cable.
On the other hand, in recent years, wireless electric power transmission that does not use a power cord or a power transmission cable becomes a focus of attention as an electric power transmission method. Three leading techniques are known as the wireless electric power transmission technique. The three leading techniques are electric power transmission using electromagnetic induction, electric power transmission using an electromagnetic wave and electric power transmission using a resonance method.
The resonance method is a non-contact electric power transmission technique such that a pair of resonators (for example, a pair of self-resonance coils) are resonated in an electromagnetic field (near field) to thereby transmit electric power via the electromagnetic field. The resonance method is able to transmit large electric power of several kilowatts over a relatively long distance (for example, several meters).
Japanese Patent Application Publication No. 2009-106136 (JP-A-2009-106136) describes a technique for wirelessly receiving charging electric power from a power supply outside a vehicle through a resonance method to thereby charge an electrical storage device equipped for the vehicle.
In addition, Japanese Patent Application Publication No. 8-163792 (JP-A-8-163792) describes a technique for reducing the size of a coil and increasing the efficiency of the coil using a ferrite core in connection with non-contact charging using electromagnetic induction.
In transmission of electric power in a non-contact manner using a resonance method, electric power is transmitted via an electromagnetic field as described above. In the resonance method, the distance of power transmission is relatively long, so it is presumable that the range of generated electromagnetic field is wider than that when electromagnetic induction is used.
The electromagnetic field generated around a coil unit including self-resonance coils may function as an electromagnetic noise for another electrical device, or the like, and, for example, it may be cause a noise of a radio, or the like. In addition, when a conductor is placed in the electromagnetic field, the conductor may be heated by electromagnetic induction caused by the electromagnetic field, so an increase in temperature may cause a failure of a device.
Therefore, in transmission of electric power using the resonance method, it is desirable to block a generated electromagnetic field in directions other than a direction in which electric power is transmitted or received, and a shield may be arranged around the coil unit.
In addition, when electric power is supplied using the resonance method, it may be necessary to reduce the size of the shield as much as possible in terms of mounting space of a vehicle.